Structure and Chemical Bonding of the B3S n 0/− (n = 2–4) Boron Sulfide Clusters: A Density Functional Theory Investigation

In search of the smallest boroxol‐type heterocyclic ring system: Planar hexagonal B3S3+ cluster with double 6π/2σ aromaticity

“…First, the cationic B 3 S 3 + cluster has a well‐defined PES (Figure 2), with cluster 1 being 1.18 eV more stable than the nearest isomer at single‐point CCSD(T). This is in contrast to the neutral B 3 S 3 cluster, 43 whose hexagonal structure 4 ( C 3 v , 2 A 1 ) is only a low‐lying isomer located 0.05 eV above the Y‐shaped GM structure 5 ( C 2 v , 2 B 2 ) (see Figure 8A). As a technical note, 4 differs slightly from the previous C 3 structure; 43 the latter has one tiny imaginary frequency and coverts to C 3 v upon optimization.…”

“…Furthermore, the type of heteroatoms from O to S is also a prerequisite for the present system. Note that both B 3 O 3 +/0/− and B 3 S 3 0/− clusters 31,43 have distinctly different structures from that of D 3 h B 3 S 3 + ( 1 ). Therefore, it is of interest to elucidate why cluster 1 (and only 1 ) adopts such a unique geometry.…”

“…In the 1960s and 1970s, mass spectroscopic studies in the gas phase confirmed the existence of a series of boron sulfide cations, suggesting that BS 2 + , B 2 S 2 + , and B 2 S 3 + are important precursors to form high molecular weight B‐S clusters 37–41 . Quite recently, computational works from us revealed rhombic B 2 S 2 and pentagonal B 3 S 2 rings in B 4 S 4 and B 3 S 2 H 3 clusters, respectively 42–44 . The D 2 h B 6 S 6 0/−/2– global minimum (GM) clusters 45 were found to contain fused twin B 3 S 2 rings with elongated overall shapes.…”

“…To achieve the above goal, the only option left to date is to thoroughly explore the title B 3 S 3 + system, because all B 3 O 3 +/0/− and B 3 S 3 0/− species do not form hexagonal rings 31,43 . In bulk B 2 S 3 crystals, 49 hexagonal B 3 S 3 and rhombic B 2 S 2 rings are linked via S bridges to form almost planar, infinite, 2D high‐polymer layers, hinting that heterocyclic B 3 S 3 rings are probably more isolable with respect to their B 3 O 3 counterparts in glassy bulk B 2 O 3 or high‐temperature B 2 O 3 liquids.…”